Assessing materials for recycling

Dr Paola Sassi of Oxford Brookes University
looks at a way of assessing specified materials
for their recycling potential.

Introduction

Environmentally conscious architects and designers are faced with difficult choices when it comes to material specification. Difficult choices because of the lack of environmental information about materials. Recycling is regarded as an effective approach to environmentally benign specification, but very little information is available to guide the specifier. The study summarised in this article considers the potential for recycling in the building industry and the indexing system developed by this study has the aim of providing guidance for architects and designers wanting to design for recycling, recycle elements of buildings or use recycled materials.

Survey results

no

SUMMARY OF MATERIALS STUDIED description of materials to be reused/ reclaimed/ reprocessed

current recycling practice

index for suitability
for
recycling

ranking

index of
benefits
from recycling

ranking

1

clay brick wall with lime mortar, to be reclaimed and reused

minimal

0.86

6

0.60

14

2

clay brick wall with cement mortar, reprocessed for hard-core

minor

0.76

13

0.51

18

3

calcium silicate bricks cement mortar, reprocessed to hard-core

major

0.76

12

0.51

18

4

dense blocks with plaster internally, reprocessed in aggregate

minimal

0.71

16

0.50

19

5

aerated blocks with external render, reprocessed in aggregate

minimal

0.79

11

0.50

19

6

aerated blocks with plasterboard, reprocessed in aggregate

minimal

0.84

7

0.50

19

7

stone ashlar walling, stones to be reclaimed and reused

minimal

0.71

16

0.56

16

8

stone cladding to external wall, to be reclaimed and reused

minimal

0.88

4

0.56

16

9

stone ashlar walling, stones to be reprocessed as hard-core

minor

0.77

12

0.51

18

10

steel welded structure, sections to be reprocessed

major

0.67

19

0.63

11

11

steel bolted structure, sections to be reused

major

0.66

20

0.76

4

12

timber structure, timber sections reused

minor

0.76

13

0.66

9

13

timber structure, reprocessed to manufacture timber boards

minimal

0.69

18

0.49

20

14

pre-cast concrete elements, to be reused

minimal

0.80

10

0.60

14

15

concrete structure, to be reprocessed to form aggregate

major

0.72

15

0.47

22

16

timber windows reused as a whole element

minor

0.77

12

0.68

8

17

timber windows disassembled and reprocessed

minimal

0.65

21

0.58

15

18

aluminium windows disassembled and reprocessed

minimal

0.71

17

0.70

7

19

profiled metal cladding coated with plastisol reprocessed

major

0.86

6

0.70

7

20

untreated timber boarding reprocessed to form board material

minor

0.88

4

0.43

25

21

profiled PVC cladding to be reprocessed

minimal

0.69

18

0.74

5

22

clay roof tiles reused

major

0.90

3

0.53

17

23

fibre cement slating to be reprocessed to hard-core

minor

0.88

4

0.45

24

24

natural slating to be reused

major

0.90

3

0.53

17

25

lead sheet roofing removed and reprocessed

major

0.82

9

0.61

13

26

aluminium sheet roofing removed and reprocessed

major

0.92

1

0.65

10

27

copper sheet roofing removed and reprocessed

major

0.91

2

0.58

15

28

zinc sheet roofing removed and reprocessed

major

0.82

9

0.53

17

29

stainless steel sheet flashings removed and reprocessed

major

0.91

2

0.66

9

30

tern coated steel sheet roofing removed and reprocessed

major

0.82

9

0.65

10

31

epdm membrane roofing reused

minimal

0.82

9

0.83

3

32

pvc membrane roofing reused

minimal

0.69

18

0.73

6

33

asphalt roofing removed and reprocessed

minimal

0.60

23

0.70

7

34

blockwork partitions, blocks reprocessed to form hard-core

minor

0.76

13

0.47

22

35

plasterboard partitions dismantled and reused

minimal

0.83

8

0.62

12

36

plasterboard partitions dismantled and reprocessed

minimal

0.74

14

0.48

21

37

timber doors removed and reused

minor

0.83

8

0.62

12

38

timber doors removed and reprocessed

minimal

0.76

13

0.48

21

39

steel doors disassembled and reprocessed

minor

0.87

5

0.70

7

40

ceramic floor finish reprocessed

minimal

0.80

10

0.46

23

41

timber floor finish reused

major

0.87

5

0.62

12

42

vinyl floor finishes reused

minimal

0.88

4

0.93

1

43

foam glass reused

minimal

0.91

2

0.53

17

44

expanded polystyrene reused

minor

0.87

5

0.86

2

45

cellulose fibre reprocessed

minimal

0.63

22

0.33

26

Conclusion

Is recycling technically feasible and environmentally desirable?
For most materials the answer is yes. Current recycling has proved in its limited extent technically successful and economically interesting. The environmental benefits are in some cases minimal and in some cases substantial, but generally undeniable. If all materials could fulfil the technical and economic requirements for recycling, they too would be recycled.

To extend the recycling practice it is paramount that in addition to the structuring of a recycled materials market, recycling itself is facilitated through new design approaches and building methods.

The new design approaches may include the use of natural, durable, non-composite, non-toxic materials and components, possibly prefabricated, in any case mechanically fixed. This would allow for reusing elements over again, until they are eventually reprocessed to produce new materials.

While the practice of recycling and designing for recycling is not widely spread, there are examples to build upon. In ten years time recycling in the building industry may become a standard procedure and designing for recycling the common approach to design.